Automatic metal louvered safety blind

ABSTRACT

Lightweight, rigid, steel shell slats extend between rigid elongated rectangular box-like frame members mounted on opposite sides of the window opening. The slats include integral heads at each end, positioned within respective frame members and captured between pairs of helically grooved contiguous worms which are both rotatably mounted within the frame members allowing driving of the same while allowing axial shifting of one worm with respect to the other to effect tilting of all of the slats simultaneously. Manual or motor means allow manual or powered, automatic tilting of the slats.

United States Patent 11 1 Larranaga [541 AUTOMATIC METAL LOUVERED SAFETY BLIND [76] Inventor: Gaston A. Larranaga, 261 Congressional Lane, Rockville, Md. 20852 [22] Filed: May 14, 1971 [21] Appl. No.1 143,340

[52] U.S. Cl ..160/169, 160/174 [51] Int. Cl. ..E06b 9/302 [58] Field of Search ..160/107, 169, 174, 23 C [56] References Cited UNITED STATES PATENTS 2,179,882 11/1939 Durre ..160/169 2,100,625 11/1937 2,855,039 10/1958 749,966 1/1904 1,244,215 10/1917 Lancaster ..160/174 1 Feb. 20, 1973 2,590,204 3/1952 Phillips ..160/236 Primary Examiner-Peter M. Caun Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Lightweight, rigid, steel shell slats extend between rigid elongated rectangular box-like frame members mounted on opposite sides of the window opening. The slats include integral heads at each end, positioned within respective frame members and captured between pairs of helically grooved contiguous worms which are both rotatably mounted within the frame members allowing driving of the same while allowing axial shifting of one worm with respect to the other to effect tilting of all of the slats simultaneously. Manual or motor means allow manual or powered, automatic tilting of the slats.

14 Claims, 18 Drawing Figures SHEET 10F 4 FIG.I

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I SHEET Q [If 4 AUTOMATIC METAL LOUVERED SAFETY BLIND BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to manually operated or electrically powered venetian blind windows of the type where the slats or louvers are independent of each other and more particularly to a heavy-duty automatic safety blind employing metal slats.

2. Description of the Prior Art Many forms of louver-type window blinds are presently in existence and incorporate various means for rotating the louvers or slats about their longitudinal axis. In most cases the louvers or slats are coupled together by bands of the material, as conventional venetian blinds, and are movable to one side or the other of the window opening. The more sophisticated and structurally complex window blinds involve the use of separate, that is, non-coupled slats which are individually traversed across the window opening and movable into spaced parallel position with respect to said opening. Where the blinds are primarily used to control the passage of light or air through the window they are generally lightweight in construction, formed of plastic or the like which flex between their points of suspension and are incapable of performing a safety function.

With rapid rise in the crime rate in this country, it is necessary for the protection of merchants and the like, as well as homeowners, to provide louvered safety blinds in which the louvers may be opened or shut at will to permit light to enter the window area during the daytime. The louvers or slats are tilted to some degree to control the transmission of light through the same or alternatively during non-business hours, the safety blind is completely closed to provide an otherwise imperforate wall overlying the window. In the most sophisticated systems it is desirous to remove completely the individual slats or louvers from view during daylight. It is to this end that the present invention is particularly directed.

SUMMARY OF THE INVENTION The automatic metal louver safety blind of the present invention comprises a rigid window frame assembly supporting a plurality of horizontally rotatable, slats or louvers which form a stack within the upper part of the frame when the blind is open. Both the drive and tilt control mechanisms are installed within two box-like frame members on each side of the window, preferably vertically oriented to allow movement of the slats under control of contiguous worms from the storage stack and into spaced parallel positions while, through vertical shifting of one worm with respect to the other, rocking or rotation of the slats occurs through an angle in an excess of 160, and from fully closed to fully open position. Safety is emphasized by employing extensions or slat heads which are securely located within the box-like frame members on each side of the window opening with the slats themselves formed of extruded thin sheet steel having a foamed inner core for lightness without sacrificing rigidity. The longitudinal edges of the slats are oppositely recessed to allow the slats to be overlapped but vertically oriented when closed for easy cleaning, etc. The frame itself may be supported by multiple hinges on one side for rotation with respect to the window opening and thus facilitate cleaning of both sides of the frame. Positive drive means insure positive positioning of the slats both in terms of vertical spacing of the same and at various angular positions relative to the axis of the slat.

Positive drive means raise and lower the slats and effect tilting of the same. The drive is achieved manually through a cranking handle and by levers or by means of electrical power. Control may be local or remote and automatic in terms of response to the sensing of daylight that is at dusk or dawn.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front sectional view of one form of the metal safety blind of the present invention.

FIG. 2 is a top sectional view of the blind of FIG. 1.

FIG. 3 is a side sectional view of the embodiment of FIG. 1 taken about line 3-3.

FIG. 4 is a sectional view of a portion of the blind of FIGS. 1 3, illustrating the worm-drive mechanism.

FIG. 5 is a fragmentary view, partially in section, of the manual lever arrangement for tilting the slats of the safety window blind of the present invention.

FIG. 6 is an elevational view of that portion of the blind shown in FIG. 5.

FIG. 7 is a fragmentary view of a portion of the tilting mechanism associated with the axially displaceable worm on each side of the window frame.

FIG. 8 is a top, sectional view of that portion of the apparatus as shown in FIG. 7.

FIG. 9 is an enlarged, sectional view of a portion of the apparatus shown in FIG. 3 illustrating the position of the continguous worm with the slats in horizontal position.

FIG. 10 is a similar view of that of FIG. 9 with one worm axially displaced to effect tilting of the slats to a full vertical position.

FIG. 11 is still another view similar to that of FIGS. 9 and 10 with axial displacement of one worm fully displaced from the position shown in FIG. 9 to illustrate tilting of the slats to an almost full position from that of FIG. 10.

FIG. 12 is a sectional view of a plurality of slats in vertically spaced, horizontal position with the worms in the position of FIG. 9.

FIG. 13 is a similar sectional view to that of FIG. 12 with the slats positioned in conformance to the axial shifting of the worm in the manner of FIG. 10.

FIG. 14 is a sectional view of the plurality of slats in positions corresponding to the axially shifted position of the worm as illustrated in FIG. 1 1.

FIG. 15 is a front elevational view of a portion of an alternative form of safety blind of the present invention.

FIG. 16 is a side elevational view of a portion of the blind illustrated in FIG. 15.

FIG. 17 is a top plan view of a portion of the blind illustrated in FIGS. 15 and 16 with the locking blade in locking position and with the blind closed.

FIG. 18 is a electrical schematic diagram of the automated control system employed in operating the embodiment of FIGS. 15 17.

DESCRIPTION OF THE PREFERRED EMBODIMENT The window blind consists generally of a metal frame including a pair of oppositely disposed box-like frame members 12 and 14 which extend vertically and are connected at their ends by a lower casing 16 and at the upper end by an upper casing 18. The upper casing 18 defines in conjunction with frame members 12 and 14, a stacking area or cavity 20 which acts to receive and stack a plurality of louvers or slats indicated generally at 22. The bottom casing 16 constitutes the housing or casing for carrying the basic drive components for the safety blind 10 which are positioned within cavity 24 and extend across the width of the window frame. The frame members 12 and 14 and the casings 16 and 18 may be formed of steel plate or other metal stock with the walls defining the same being coupled together by welding the same or by nuts and bolts, screws or the like in conventional practice. The upper and lower casings 16 and 18 may fit within and be hidden by recesses within the building walls housing the same so as to expose only the safety blind window area 25 within which are selectively positioned, vertically spaced slats or louvers 22.

Of particular importance to the present invention is that fact that the side frame members 12 and 14 are box-like in form including an outer end wall 26. Inner wall 28 carries a central elongated slot or'opening 30 and side walls 32 join the same to define a frame member cavity 34. Within the cavity 34, extend preferably, a pair of contiguous nylon plastic worms 36 and 38 for the left-hand frame member 12 and 40 and 42 for the right-hand frame member 14. The worms are each fixed to an axial support or drive shaft 44 and in fact the nylon worms may be molded or extruded directly on to their rods 44. The rods 44 are mounted within fixed nylon or metal sleeve bearings 46 at spaced longitudinal positions. The bearings 46 are fixedly positioned with respect to the frame members 12 and 14 such that the rods 44 and thus the worms rotate about their axes. The nylon worms are self-lubricated and carry a helical groove 48 having rounded edges 50 but otherwise being of rectangular cross sectional configuration, while adjacent to the slots are provided arcuate or circular grooves 52 of the same pitch and defining in similar fashion, either right-hand or left-hand thread as the case may be. The purpose of the rectangular groove 48 and its adjacently positioned circular groove 52 is to effect the positioning, tilting, and drive to the individual slats or louvers 22 during operation of the safety blind.

In this respect, each of the slats is formed of thin steel stock in terms of an outer casing 54 and has a foam inner core 56. The casing 54 is provided with oppositely disposed recessed edges 58 which cooperate with similar recesses within adjacent slats such that when the blind is fully closed as indicated in FIG. 13, the recessed edges overlap to effect a generally flat unbroken wall. The steel shell as at 54 provides the strength necessary to provide a safety function by the blind, while the foam core 56 insures rigidity while assisting in keeping the slats lightweight since they must be moved from the stacking area 20 into an appropriate vertically spaced position by either manual or motor drive mechanisms hereinafter described. The core 56 may be of polyethylene or polystyrene foam or the like. Nylon balls 60 are rigidly fixed to the four corners of the slats and effect, in conjunction with the helical grooves 48 and 52, a means for both tilting the slats or louvers 22 and moving the same from the stacking area into proper, vertically spaced position. While the slats 22 may be perfectly flat, as shown in FIGS. 12, 13 and 14 they are essentially diamond shaped in cross-sectional configuration. Further the slats include a rigid metal strip 62 extending centrally through the same and act as a reenforcing means for foam core 56. This may be eliminated if necessary or alternatively the strip 62 may extend from each end of the slat or louver and constitute the slot head or extension 64. In this respect, it should be noted that the slot head 64 carrying the nylon balls is less than the width of the guide slot or opening 30 within the inner or safety wall 28 of each of the frame members 12 and 14, is smaller in width than the main portion of the louver or slat 22 and is also smaller than the distance between the outside edges of the two nylon balls 60 at respective corners of the slot head 64. Thus, since the frame member is box-like in configuration and is formed of steel or other sheet metal and since the presence of the nylon balls which are fixed to the head of the slat prevent withdrawal of the slats from the frame member, it is almost impossible to open the louvered steel safety blind 10 of the present invention when the slats are closed especially in the overlapped fashion of FIG. 13.

In addition, it is this arrangement which facilitates the tilting and drive of the individual slats defining the louver window assembly. Reference to FIG. 3 illustrates in particular, the unique method of effecting both the positive drive movement of the individual louvers or slats from the stacking area 20 into proper. vertically spaced positions within the window opening area 25 and the tilting of the individual slats simultaneously about their axis, by axial shifting of one of the worms with respect to the other. As mentioned previously, bearing blocks 46 act to support and locate the worms for rotation within the frame members. Blocks 46 at the top of the frame members carry the ends of the mounting rods 44 for the respective worms, FIG. 3, in this case worms 40 and 42. Fixed to the top to theworms are circular metal discs which include sector shaped openings 72 in the area of termination of the rectangular groove 48. The edges of the discs are sharp on both sides of the openings 72 to insure when in oppositely disposed alignment, as illustrated in FIG. 2 the balls at the corners of the slat heads 64 move readily into the helical grooves 48 and shift longitudinally of the worm in a manner controlled by the rotation of the worms. FIG. 3 illustrates movement of one of the slats into drive engagement with the rectangular drive grooves 48 of the contiguous worms 40 and 42, while a plurality of additional slats 22 remain in vertically stack position within the stacking area 20 of the window frame. Additional slats 22 are already positioned at vertically displaced positions defined by the pitch of the worms so as to effect when overlapped, a closed and imperforate wall as illustrated in FIG. 13. The rods 44 for respective worms extend beyond the bottom of the window opening 21 and are supported in similar fashion by bearing blocks 46 allowing rotation of the rods and thus the nylon worms. In this respect, the worm 36 is provided at its lower end with a spur gear 76 of relatively large axial length. Gear 76 is mounted with respect to bearing blocks 46 for limited axial shifting as indicated by double-headed arrow 78. In this respect, worm 42 is provided with lower bearing block 46 which is fixed to lower casing 16 and receives the lower end of the worm rod 44. It carries a much smaller spur gear 80 which is in mesh with the larger axially elongated spur gear 76, however, during axial shifting of worm 40 with respect to worm 42 these gears 76 and 80 are in continuous mesh. The lower casing 16 supports a manual drive mechanism consisting of a bearing 84 supporting a square-headed drive shaft 86 having fixed to the inner end thereof a helical drive gear 88, which is in turn, in mesh with bevel gear 90 fixed to shaft 44 of the righthand drive worm 42. Thus, by engaging the headed end of drive shaft 86 with a crank (not shown) or the like, inserted within casing opening 92 provided within safety bar 94, the drive gear 88 may be rotated manually to effect positive rotation of all four worms to facilitate the removal of the slats 22 from the stacking area 20 and the filling of the window with the appropriate number of slats at vertically spaced positions or vice versa. The slats moved downwardly by means of balls 60 which generally fill the grooves 48 of helical worms. Reference to FIGS. 1 and 3 illustrates the means of driving all four worms from one side only in this case the transmission cavity 24 carries, by means (not shown), a horizontal coupling shaft 96 having bevel gear 98 on one end and a second bevel gear 100 on the opposite end which is in mesh with bevel gear 102 associated with non-axially shiftablc nylon drive worm 38 within left-hand frame member 12. The worm 38 is also provided with a spur gear 80 which effects driving of the axially shiftable worm 36 by a mating spur gear 76. I In order to effect tilting of the louvers from the extreme positions shown in FIGS. and 11 through the horizontal position shown in FIG. 12, worms 36 and 40 are shifted relative to axially fixed drive worms 38 and 42. Bearing blocks 46 are positioned sufficiently above plate 70 at the upper ends of worms 36 and 40 and the lower support bearing 46 is spaced sufficiently below thesame worm through which rod 44 extends, so as to permit axial shifting of the worms, rods 44 and all of the elements carried thereby. In this respect, the operating lever 104, shown in greater detail in FIGS. 5 and 6, operates the crank arm 106 which extends within the housing and terminates, FIG. 7 in a right-hand extension 107 and is thereby coupled to lever 108. The opposite end of the lever 108 is coupled to a crank arm 110, via arm 1 14. Thus, rotation of operating lever 104 causes simultaneous rotation of crank arms 106 and 110 associated with the nylon worms 36 and 90. Axial shifting of these worms between extreme positions and the effect thereby, with respect to the contiguous axially fixed worms 38 and 42 is illustrated in FIGS. 9, 10, and 11. The operating lever 104 is fixed to crank arm 106, lies exterior of housing 16, and carries at the opposite end a handle 118. Intermediate of its ends, there extends upwardly via a pin connection 120, a safety bar 94 in the form of a metal strip 122 which terminates in an off-set portion 124 which carries opening 92 which is aligned with fixed opening 91 only when the axially shiftable worms are in a position such that the slats are horizontally positioned as shown in FIG. 3. Any shifting of operating lever 104 to a position other than that shown in full lines in FIGS. 6 and 7, results in vertically shifting and misalignment of openings 91 and 92. Thus the crank normally used in driving the slats upward into the storage area 20 can not be coupled to the end of drive shaft 86 and thus manually stacking of the slats is impossible when the slats are other than fully open, for instance in either the positions of FIGS. 13 or 14.

Since it is desirable to incline the slats or louvers so as to shade the interior of the building carrying the window while permitting some light to enter in the fashion of conventional venetian blinds, means are provided to frictionally lock the operating lever 104 in any position between the extreme dotted line positions shown in FIG. 7. In this respect the handle carries a cylindrical casing 124 with an opened end receiving braking disc or plug 126 which fits within the center of the same and is biased by compression spring 128 into contact with the wall of casing 16. The pressure of the same is adjusted by the threaded plug 130 carried at the outboard end of the cylindrical casing. A pair of rivets 132, FIG. 4 on each side of the safety bar 94 act as fixed guides for the bar during its vertical movement.

The cooperation between the transport grooves 48 and the self-lubricating nylon balls 60, the rounded edges 50 of grooves 48 and the cooperating circular cross-sectional grooves 52 adjacent the rectangular groove 48 may be seen by further reference to FIGS. 10 and 11. In addition, under the arrangement of the present invention, a very short axial shift in one of the self-lubricating nylon worms with respect to the other and its effect in tilting simultaneously all of the slats carried by the contiguous worm may be readily appreciated. The gap distance Y between the peripheries of the contiguous worms such as worms 40 and 42 for instance is less than the diameter of the balls 60 so that at no time can the slats fall vertically under gravity influence between laterally spaced worms. This is best illustrated in FIG. 10 where the slats have all been moved into full vertical position, the upper ball 60 being captured between the shallow curved groove 52 of worm 40 and the rounded edge 50 of rectangular groove 48 of the opposed worm 40. In moving from fully closed to fully open position, the balls at the corners of the slat heads rotate 168 from the vertical. In the illustrated embodiment of FIGS. 9 to 14, in which the slats have a nominal width of 2 inches and in which case, for a 15 millimeter vertical displacement of each slat, the same is tilted through 156 by axial shifting of the axially moveable worm with the respect to the fixed worm. A vertical rise of 15 millimeters will cause the slats to be tilted through 156 from the position shown in FIG. 10 to that of FIG. 11. Approximately 10 inches of height are required in the upper casing in order to stack 25 slats for an open window space of some 43% inches, which is standard. It may be necessary to recess the upper casing and to therefore hide this recessed portion of the window since it would otherwise detract from the appearance of the window to which the automatic steel blind of the present invention is employed. The parameters mentioned above are exemplary only but illustrate in a practical sense, some of the relationships between the elements of the present invention. The safety blind of the type described above is of simplified construction and lasts longer than the prior art devices. It is smooth and positive in function and operation and provides the additional benefit of ease and control of all functions and from the same side whether either hand or electrically operated.

Referring to the embodiment of FIGS. through 18 inclusive, FIG. 15 is a fragmentary, sectional elevation of a portion of the safety blind and constitutes in turn, a portion similar to that found in the right-hand lower corner of FIG. 1. In that respect and in respect to the other figures illustrating this embodiment, like numerals designate like components to that of the first embodiment. Wall 28 of right-hand frame member 14 houses the contiguous worm 42 which is visible in FIG. 15 and fixed to worm support and drive rod 44. This rod 44 is splined at 45 and is shiftable axially, as indicated by the double-headed arrow within spline gear support member 300. Spline member 300 supports a spur gear 302. In that respect, a U-shaped support member 304 coupled at one end to vertical frame member 306 supports both spur gear 302 which is spline connected to worm 42 and the inter-meshed spur gear 308 which is spline connected by a spline 310 to worm 40 which is contiguous to worm 42. Thus, in the case of this embodiment regardless of axial shifting of worms 40 and 42 which are both axially shiftable, the gear connection between the worms remains in effect although the spur gears 302 and 308 are themselves not shifted axially.

In similar manner to the first embodiment, the lower casing 16 includes an opening 314 through which projects an operating lever 316 which is coupled to a transversely extending central tilt shaft 318 for simultaneous shifting of both pairs of contiguous worms. Arms 320 and 322 extend to opposite sides of the pivot axis of shaft 318 with the ends of these arms being coupled by ball and socket joints 321 and 323 to support rods or shafts 44 for worms 40 and 42 respectively for the right hand frame member 14. The opposite frame member carries identical members. Obviously, oscillation of operating lever 316 effects simultaneous shifting of the worms along their axis, but in opposite directions.

Importantly, a portion of the right hand frame member 14 is modified at the bottom to include spaced vertical support plates 324 and 326, supporting a drum 328 for rotation about a vertical axis parallel to the axis of the adjacent worm 42. Extending upwardly from drum 328 is a locking blade support shaft 330 to which is attached a rectangular locking blade 332. Thus, rotation of the drum 328 and shaft 330 causes the locking blade to swing from a dotted line position shown in FIG. 17 to a full line or locking position with respect to the vertically oriented slat 22 in the same Figure. Only when the salts are fully closed can the locking blade 332 be moved to the full line position. In order to achieve this automatically and to prevent the same from occurring during positioning of the slats in their normal horizontal position or at right angles to the axis of the worms, the periphery of the drum 328 carries a helical groove 338 within which is received pin 336 carried by a link 334 which is pivoted at its opposite end to operate a lever 316. In a simple manner, oscillation of operating lever 316 is converted to rotary motion of the drum 328 by the groove 338 which acts as a follower resulting in rotation of the locking blade 332 about the axis of shaft 330 and drum 328.

In order to drive electrically the two sets of contiguous worms, a plastic sprocket and chain coupling arrangement is illustrated at 342 which positively couples the support shafts 44 for worms 40 and 36, the

sprocket being fixed to each drum supporting shaft and a chain extending therebetween.

Referring to FIG. 18 it is assumed that motor 344 has its output shaft 346 coupled directly to the sprocket drive system such as 342 of the illustrated embodiment of FIGS. 15 through 17. Further, terminals illustrated at 1, 2, and 3 in FIG. 18 are connected to terminals 1, 2, and 3 for solenoid 340 in FIG. 17 to effect manually initiated or automatically controlled, electrically operated, axial shifting of the worms to achieve tilting to the desired degree of the individual slats. An appropriate AC power supply is connected to terminal 340, the power being rectified by means of rectifier 350 for supply to either solenoid 340 or the drive motor 344 under the automatic or manually initiated control system illustrated in FIG. 18. In that respect, the system incorporates a photo-cell 352 which is coupled through amplifier 354 to a relay coil 356 which, upon proper energization opens the supply of current between contacts l and 2 for instance and closes the supply of current through contacts 2 and 3 to the portion of the solenoid coil 340 which appropriately shifts the slats from their fully vertical or closed position to a fully open or horizontal position by relatively shifting both worms 40 and 42 for instance simultaneously. Through the sprocket drive system 342 and through shaft 318 extending across and being mechanically coupled to worms 36 and 38 on the opposite frame member 12, all four worms shift simultaneously depending upon the state of energization of relay coil 356. In addition the manually operated three-position switch SW-l is moved to either up or down position or remains at neutral to control the application of power to motor 344 to drive the worms simultaneously. With the slats preferably in horizontal position they move up into the storage area 20 or move from the storage area and are distributed equally, depending upon the helical pitch of the worm, at various longitudinal locations throughout the frame members. A micro switch SW-2 associated with the hand operating crank (not shown) prevents energization of drive motor 344 by the hand operated switch SW-l if in fact hand cranking is employed to move all of the slats into the storage 20 or remove the same. Additional micro switches SW-3 and SW-4, which are shown as normally closed, are open under control of the slats and are activated only by the presence or absence of an appropriate slat. Whenever deactivated by the last slat to be raised or the same slat reaching its lower most position, the motor current is automatically interrupted preventing the motor 344 from driving the worms to any further extent. However, depending upon whether the motor is driving the slats up or down reverse direction drive is permissible even if one of the normally closed switches SW-3 or SW-4 is opened since, obviously the other one must be closed at that time. The manually operated switch sW-6 constitutes a 3-position switch with a neutral central position, this switch being activated to drive the solenoid core constituting an integral portion of rod 44 associated with worm 40 to either an up or down position with respect to solenoid core portions as defined by taps 1, 2 and 3 FIG. 17. Thereby, through manual operation of the switch SW-6 motorized tilting occurs without the necessity of manually tilting lever 316, whereby the slats move to full horizontal position or 90 thereto, that is, at full vertical position depending upon which portion of the coil is energized.

What is claimed is:

1. A louver-type safety window blind assembly comprising: elongated rectangular box-like frame members mounted on opposite sides of the window opening in spaced parallel fashion, pairs of helically grooved worms carried respectively by each frame member in spaced, parallel, contiguous fashion, a plurality of separate slats extending across the window opening and terminating in edge engagement with the grooves of respective worms, means for shifting one of said contiguous worms axially with relation to the other to effect tilting of said slats and means for rotating both pairs of said contiguous worms simultaneously in opposite directions to cause said slats to travel lengthwise of said worms.

2. The assembly of clam 1 wherein nylon balls are fixed to the corners of said slats and are carried within the helical grooves of respective contiguous worms to facilitate slat movement lengthwise of the rotatable worms.

3. The assembly of claim 2 wherein the inner wall of each frame member includes a narrow longitudinal opening extending lengthwise of the same, said slats terminate in integral heads laying within said frame member internally of said longitudinal openings, the distance between the peripheral extremities of the nylon balls on opposite corners of the same slat head being in excess of the width of said longitudinal opening within the inner wall of each frame member whereby, regardless of the position of said slats with respect to the frame member supporting the same, the slats resist removal from said frame member.

4. The assembly of claim 3 further comprising a second helical groove in circular cross-section formed within each of said worms adjacent to the drive groove and having a pitch identical thereto, the spacing between contiguous worms being less than the diameter of said balls to facilitate tilting of said slats about the longitudinal axis thereof but preventing slippage of said slats between said contiguous worms during relative axial shifting of the same.

5. The assembly of claim 4, wherein gear means couple said contiguous worms for positive rotation of the same in opposite directions and said assembly further comprises bevel gear drive means extending laterally from one frame member to the other to effect positive drive therebetween.

6. The assembly of claim 5, wherein said slats are in the form of metal shells filled with foam material, the pitch of said worms and the width of the slats being such that the edges of the slats overlap slightly when fully closed, and said longitudinal edges being respectively, reversely recessed so as to provide a smooth continuous surface when the blind is fully closed with said edges overlapped.

7. The assembly of claim 3, wherein said means for shifting said contiguous worms axially relative to each other to effect tilting of said slats includes lever means extending across the lower ends of said frame members for coupling said axial shiftable worms within respective frame members, an operating handle exterior of said casing is operatively coupled to said lever means for axially shifting said worms, and wherein said means for oppositely rotating said contiguous worms comprises a manual gear drive mechanism including a crank receiving drive shaft within said casing accessible from the casing exterior and said operating handle includes means preventing access to said crank receiving shaft when said slats are other than at right angles to the axis of said contiguous worms.

8. The assembly of claim 7, wherein said access preventing means comprises; a plate fixed to said operating handle and movable therewith and an opening within said plate movable into alignment with said crank receiving drive shaft.

9. The assembly of claim 8, wherein said operating handle includes friction brake means spring biased into contact with said casing for maintaining said operating handle at a desired position to maintain said slats in a tilted position as determined by the angular position of said operating handle.

10. The assembly of claim 3, wherein said contiguous worms are fixed to coaxially shiftable support rods and said assembly further includes splined gears for each of said contiguous worms in constant mesh and concentrically carried by respective worm support rods, said lower casing carries an arm pivoted intermediate of said support rods for contiguous worms and having ball joints at each end thereof coupled to respective rods and an operating lever operatively coupled to said arm for rotating the same about its pivot axis to effect sim ultaneous axial shifting of said worms in opposite directions.

11. The assembly of claim 10, further comprising a locking plate pivotably mounted about an axis parallel to the axis of said contiguous worms and extending adjacent thereto, a cylindrical drum coupled to said locking plate for rotation about a common axis, a helical groove formed within the drum periphery, lever means pivotably coupled at one end to said operating lever and including a follower drive pin at the opposite end engaging said helical groove whereby oscillation of said operating lever causes rotationof said drum and pivoting of said locking plate into locking position such that its outer edge abuts the slats which are moved into edge overlapped and closed position automatically in response to oscillation of said operating lever.

12. The assembly of claim 6, wherein said contiguous worms are fixed to coaxially shiftable support rods ahd said assembly further includes splined gears for each of said contiguous worms in constant mesh and concentrically carried by respective worm support rods, said lower casing carries an arm pivoted intermediate of said support rods for contiguous worms and having ball joints at each end thereof coupled to respective rods and an operating lever operatively coupled to said arm for rotating the same about its pivot axis to effect simultaneous axial shifting of said worms in opposite directions.

13. The assembly of clam 1 further comprising:

a locking plate movably mounted on one of said frame members and extending parallel to the frame member and at right angles to longitudinal axis of said slats,

cal groove formed within the drum periphery, lever means pivotably coupled at one end of said operating lever and including a follower drive pin at the opposite end engaging said helical groove whereby oscillation of said operating lever causes rotation of said drum and pivoting of said locking plate into locking position,

such that its outer edge abuts the slats which are moved into edge overlapped and closed position automatically in response to oscillation of said operating lever. 

1. A louver-type safety window blind assembly comprising: elongated rectangular box-like frame members mounted on opposite sides of the window opening in spaced parallel fashion, pairs of helically grooved worms carried respectively by each frame member in spaced, parallel, contiguous fashion, a plurality of separate slats extending across the window opening and terminating in edge engagement with the grooves of respective worms, means for shifting one of said contiguous worms axially with relation to the other to effect tilting of said slats and means for rotating both pairs of said contiguous worms simultaneously in opposite directions to cause said slats to travel lengthwise of said worms.
 1. A louver-type safety window blind assembly comprising: elongated rectangular box-like frame members mounted on opposite sides of the window opening in spaced parallel fashion, pairs of helically grooved worms carried respectively by each frame member in spaced, parallel, contiguous fashion, a plurality of separate slats extending across the window opening and terminating in edge engagement with the grooves of respective worms, means for shifting one of said contiguous worms axially with relation to the other to effect tilting of said slats and means for rotating both pairs of said contiguous worms simultaneously in opposite directions to cause said slats to travel lengthwise of said worms.
 2. The assembly of clam 1 wherein nylon balls are fixed to the corners of said slats and are carried within the helical grooves of respective contiguous worms to facilitate slat movement lengthwise of the rotatable worms.
 3. The assembly of claim 2 wherein the inner wall of each frame member includes a narrow longitudinal opening extending lengthwise of the same, said slats terminate in integral heads laying within said frame member internally of said longitudinal openings, the distance between the peripheral extremities of the nylon balls on opposite corners of the same slat head being in excess of the width of said longitudinal opening within the inner wall of each frame member whereby, regardless of the position of said slats with respect to the frame member supporting the same, the slats resist removal from said frame member.
 4. The assembly of claim 3 further comprising a second helical groove in circular cross-section formed within each of said worms adjacent to the drive groove and having a pitch identical thereto, the spacing between contiguous worms being less than the diameter of said balls to facilitate tilting of said slats about the longitudinal axis thereof but preventing slippage of said slats between said contiguous worms during relative axial shifting of the same.
 5. The assembly of claim 4, wherein gear means couple said contiguous worms for positive rotation of the same in opposite directions and said assembly further comprises bevel gear drive means extending laterally from one frame member to the other to effect positive drive therebetween.
 6. The assembly of claim 5, wherein said slats are in the form of metal shells filled with foam material, the pitch of said worms and the width of the slats being such that the edges of the slats overlap slightly when fully closed, and said longitudinal edges being respectively, reversely recessed so as to provide a smooth continuous surface when the blind is fully closed with said edges overlapped.
 7. The assembly of claim 3, wherein said means for shifting said contiguous worms axially relative to each other to effect tilting of said slats includes lever means extending across the lower ends of said frame members for coupling said axial shiftable worms within respective frame members, an operating handle exterior of said casing is operatively coupled to said lever means for axially shifting said worms, and wherein said means for oppositely rotating said contiguous worms comprises a manual gear drive mechanism iNcluding a crank receiving drive shaft within said casing accessible from the casing exterior and said operating handle includes means preventing access to said crank receiving shaft when said slats are other than at right angles to the axis of said contiguous worms.
 8. The assembly of claim 7, wherein said access preventing means comprises; a plate fixed to said operating handle and movable therewith and an opening within said plate movable into alignment with said crank receiving drive shaft.
 9. The assembly of claim 8, wherein said operating handle includes friction brake means spring biased into contact with said casing for maintaining said operating handle at a desired position to maintain said slats in a tilted position as determined by the angular position of said operating handle.
 10. The assembly of claim 3, wherein said contiguous worms are fixed to coaxially shiftable support rods and said assembly further includes splined gears for each of said contiguous worms in constant mesh and concentrically carried by respective worm support rods, said lower casing carries an arm pivoted intermediate of said support rods for contiguous worms and having ball joints at each end thereof coupled to respective rods and an operating lever operatively coupled to said arm for rotating the same about its pivot axis to effect simultaneous axial shifting of said worms in opposite directions.
 11. The assembly of claim 10, further comprising a locking plate pivotably mounted about an axis parallel to the axis of said contiguous worms and extending adjacent thereto, a cylindrical drum coupled to said locking plate for rotation about a common axis, a helical groove formed within the drum periphery, lever means pivotably coupled at one end to said operating lever and including a follower drive pin at the opposite end engaging said helical groove whereby oscillation of said operating lever causes rotation of said drum and pivoting of said locking plate into locking position such that its outer edge abuts the slats which are moved into edge overlapped and closed position automatically in response to oscillation of said operating lever.
 12. The assembly of claim 6, wherein said contiguous worms are fixed to coaxially shiftable support rods and said assembly further includes splined gears for each of said contiguous worms in constant mesh and concentrically carried by respective worm support rods, said lower casing carries an arm pivoted intermediate of said support rods for contiguous worms and having ball joints at each end thereof coupled to respective rods and an operating lever operatively coupled to said arm for rotating the same about its pivot axis to effect simultaneous axial shifting of said worms in opposite directions.
 13. The assembly of clam 1 further comprising: a locking plate movably mounted on one of said frame members and extending parallel to the frame member and at right angles to longitudinal axis of said slats, and means for moving said locking plate from a first position allowing free tilting of the slats to a second locking position immediately adjacent said slats when in closed position and at right angles to prevent tilting and opening of the same. 